1. Field of the Invention
The present invention relates to a driven roller unit and a paper feeding device, and more particularly relates to a driven roller unit capable to balance the force exerting thereon and a paper feeding device using the driven roller unit and capable to prevent paper from skewing.
2. Description of Related Art
FIG. 1 is a schematic view of a conventional paper feeding device. Referring to FIG. 1, the conventional paper feeding device 100 is adapted to be assembled on the base (not shown) of the multi-function printer and includes an driving roller 110, a driven roller 120 and a frame 130, wherein the frame 130 may be fixed on the base of the multi-function printer, and the frame 130 has a recess 132 with a shape corresponds with the driven roller 120, and the rod-shaped driven roller 120 is disposed in the recess 132 of the frame 130.
In general, the printed document may often skew due to the tilt of the paper during paper feeding process. The reason of paper skew is probably because a bad parallelism is formed between the driving roller 110 and the driven roller 120 of the paper feeding device 100, or because the pressure exerting from the driving roller 110 to the driven roller 120 is not uniformly distributed. It needs a mechanism to control the parallelism between the driving roller 110 and the driven roller 120. In other words, the assembly precision and tolerance of the components are required to be so good and thus the cost of components and human labor for assembling is further increased. In addition, so far in current technology, the parallelism between the driving roller 110 and the driven roller 120 cannot be automatically calibrated. Moreover, the crimp depth of the driving roller 110 exerting on the driven roller 120 cannot be precisely controlled by mechanism, and thus the problem of uneven distributed force exerting on the driven roller 120 has not been unable to be effectively improved.